tannin, fulvic acid, synthetic humic substances


This research introduces a new, simple and effective method of producing synthetic fulvic acids from tannin. The synthesis is based on the reaction of tannin oxidation by pure oxygen in a highly alkaline environment. The conversion of fulvates to the acid was achieved by passing the resulting mixture through a cation-exchange column in the H-form. The resulting dark-brown product solution has a pH = 2. A complex study of the physicochemical and spectroscopic properties of the obtained product using the methods of elemental analysis, ultraviolet-visible, infra red and electron paramagnetic resonance spectroscopy, scanning electron microscopy, X-ray diffraction showed the similarity of the obtained product to natural fulvic acids. Synthetic fulvic acids are advantageous over natural humic substances due to their reproducible properties as a result of their strict synthesis conditions. This significantly expands the scope of their application, in particular in medicine, where one of the prerequisites is the standardization of properties.

Author Biographies

Valentina A. Litvin, Bohdan Khmelnitsky National University of Cherkasy

Department of Chemistry and Nanomaterial Science, Associate professor, PhD

Roger Abi Njoh, Near East University

Department of Toxicology, PhD student


Gomes de Melo, B. A., Motta, F. L., Santana, M. H. (2016). Humic acids: Structural properties and multiple functionalities for novel technological developments. Mater Sci Eng C., 62, 967–974.

Rigobello, E.S., Campos, S.X., Vieira, E.M. (2017). Comparative characterization of humic substances extracted from freshwater and peat of different apparent molecular sizes. Rev. Amb. Água., 12, 774–785.

Senesi, N., Xing, B., Huang, P.M. (Eds.). (2009). Biophysico-Chemical Processes Involving Natural Nonliving Organic Matter in Environmental Systems. John Wiley & Sons, Inc.

Kulikowska, D. (2016). Kinetics of organic matter removal and humification progress during sewage sludge composting. Waste Management, 49, 196–203.

Eller, W. (1923). Studien über huminsäuren. IV. Darstellung und eigenschaften künstlicher und natürlicher huminsäuren. Liebigs Ann. Chem., 431, 133–161.

Welte, E., Schatz, M., Ziechmann W. (1910). Über synthesehuminsäuren (Oxydationsmessungen) Naturwiss, 41 (9), 213–214.

Cataldo, F. (1998). On the structure of macromolecules obtained by oxidative polymerization of polyhydroxyphenols and quinines. Polym. Int., 46, 263–268.<263::AID-PI983>3.0.CO;2-0

Cherepanov, I. S., Kryukova, P. S. (2020). Formation of humic substances in the reaction of D-glucose with p-toluidine in anhydrous ethanol. Proceedings of universities. Applied chemistry and biotechnology, 10 (2), 188–195.

Sławińska, D., Polewski, K., Rolewski, P., Sławiński, J. (2007). Synthesis and properties of model humic substances derived from gallic acid. Int. Agrophys, 21, 199–208.

Litvin, V.A., Minaev, B.F., Baryshnikov, G.V. (2015). Synthesis and properties of synthetic fulvic acid derived from hematoxylin. J. Mol. Struct., 1086, 25–33.

Yang, T., Hodson, M. E. (2018). The copper complexation ability of a synthetic humic-like acid formed by an abiotic humification process and the effect of experimental factors on its copper complexation ability. Environmental Science and Pollution Research, 25, 15873–15884.

Hänninen, K.I., Klöcking, R., Helbig, B. (1987). Synthesis and characterization of humic acid-like polymers. Sci. Total Environ., 62, 201–210.

Jung, A.-V., Frochot, C., Parant, S., Lartiges, B.S., Selve, C., Viriot, M.-L., Bersillon, J.-L. (2005). Synthesis of amino-phenolic humic-like substances and comparison with natural aquatic humic acids: A multi-analytical techniques approach. Org. Geochem., 36, 1252–1271.

Giannakopoulos, E., Drosos, M., Deligiannakis, Y. (2009). A humic-acid-like polycondensate produced with no use of catalyst. J. Colloid Interface Sci., 336, 59–66.

Laub, R. J. (1999). US Patent No. 5945446. Newport Beach, Calif.: US.

Wang, X., Muhmood, A., Dong, R., Wu, S. (2020). Synthesis of humic-like acid from biomass pretreatment liquor: Quantitative appraisal of electron transferring capacity and metal-binding potential. Journal of Cleaner Production, 255, 120243.

Ziechmann, W. (1960). Über modellreaktionen zur bildung synthetischer huminsäuren. 2. Die synthese von huminsäuren im neutralen milieu. Brennstoff-Chem., 41, 334.

Ikan, R., Dorsey, T., Kaplan, I. R. (1990). Characterization of natural and synthetic humic substances (melanoidins) by stable carbon and nitrogen isotope measurements and elemental composition. Anal. Chim. Acta, 232, 11.

Matthiessen, A. (1995). Determining the redox capacity of humic substances Vom Wasser., 84, 229–235.

Hoyos-Martinez, P., Merle, J., Labidi, J., Bouhtoury F.C. (2019). Tannins extraction: A key point for their valorization and cleaner production. J. Clean. Prod., 206, 1138–1155.

Aires, A. (Ed.). (2019). Tannins: Extraction from Plants. UK, London: IntechOpen.

Machadoa, W., Franchini, J. C., de Fátima Guimarães, M, Filho, J.T. (2020) Spectroscopic characterization of humic and fulvic acids in soil aggregates, Brazil. Heliyon, 6(6), e04078.

Zhang, Y., Gong, G., Zheng, H., Yuan, X., Xu L. (2020). Synergistic Extraction and Characterization of Fulvic Acid by Microwave and Hydrogen Peroxide–Glacial Acetic Acid to Oxidize Low-Rank Lignite. ACS Omega, 5(12), 6389–6394.

Filcheva, E., Hristova, M., Nikolova, P., Popova, T., Chakalov, K., Savov, V. (2018). Quantitative and qualitative characterisation of humic products with spectral parameters. J. Soils Sediments, 18, 2863–2867.

Struyk, Z., Sposito, G. (2001). Redox properties of standard humic acids. Geoderma, 102, 329–346.